Intensity modulated radiation therapy (IMRT) is a treatment method for cancer patients requiring radiation treatment. IMRT is an extremely precise method of treatment delivery where the radiation dose conforms to the target and avoids the surrounding critical structures. Rather than having a single large radiation beam pass through the body, with IMRT the treatment is delivered from various angles and the intensity of the radiation beam is varied across the treatment area.
The radiation is effectively broken up into thousands of tiny pencil-thin radiation beams. With millimeter accuracy, these beams enter the body from many angles and intersect on the cancer. This results in a high radiation dosage to the tumor and a lower radiation dose to the surrounding healthy tissues.
One method for modulating the intensity of the radiation beam is based upon moving a multi-leaf collimator (MLC) in and out of the radiation beam from the radiation treatment machine. An MLC comprises a plurality of thin width mechanical blades or leaves, which are individually controlled by miniature motors and mechanical drive linkages. A computer controls the miniature motors for driving the individual blades in and out to shape the radiation beam. An advantage of an MLC based IMRT treatment machine is that the same MLC can be automatically controlled to support the individual needs of each patient receiving radiation treatment. In other words, the MLC is reconfigured for each new patient. Unfortunately, the cost for an MLC can easily exceed a half million dollars.
A more cost effective method for modulating the intensity of the radiation beam is based upon the use of a compensator. The compensator (also referred to herein as a radiation filter) used by the radiation therapy machine is specifically designed for that patient. The cost of such a filter is less than a couple of hundred dollars.
A compensator type radiation filter is machined from a solid piece of material (referred to herein as a radiation filter blank), and is mounted directly in the path of the radiation beam. The unique three-dimensional geometry of each machined radiation filter provides the conformal radiation dose distributions required by the cancer patient.
Since each radiation filter must be individually machined from a radiation filter blank, a compensator type radiation filter cannot be reused on other cancer patients. The radiation filter may be machined in-house by a radiation treatment center, or alternatively, it may be ordered from an outside machine shop.
Once an order is received by an outside machine shop, a number of information related tasks need to be performed before a radiation filter blank is actually machined into a radiation filter. For example, modeling and programming functions need to be determined. In addition, for each radiation filter machined, it must be properly labeled and verified for accuracy. Consequently, each order for a radiation filter requires a considerable amount of employee intervention before the filter is actually packaged and shipped.
One example of an outside machine shop providing radiation filters of this type is Medicalibration located in Ripon, Calif. Medicalibration receives orders via e-mail, wherein the e-mail includes design data for the radiation filter. Once the design data is received, the above noted steps are to be performed before the filter is packaged and shipped. If the number of orders being processed on a daily basis is small, then the required employee intervention is not a limiting factor. In contrast, if the number of orders being processed on a daily basis is large, then the required employee intervention can be a limiting factor.